6 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
On argillaceous schist, foothills of the Santa Monica Mountains near the Soldiers’ 
Home. 
Type deposited with Dr. W. Nylander in 1897; duplicates in the U.S. National 
Herbarium and in herb. Hasse (‘‘E stirpe V. polysticta” Nyl. in litt.). 
10. Verrucaria maura Wahlenb. 
Thallus black, minutely rimose and papillate; perithecium of medium size, dimidi- 
ate, internally dark; paraphyses none; spores 8, oblong, 12 to 15 we long, 7 to 8 « thick; 
hymenial gelatine vinous red with iodine. 
On calcareous beach rocks near Newport and San Pedro, also on Santa Catalina 
Island. Reported from South America, Europe, northern Asia, and Africa, 
THELIDIUM Maas. 
Thallus crustaceous, thin, uniform, diffuse; hypothallus obsolete; spores 2 to 4- 
locular. 
1. Thelidium microbolum (Tuck.). 
Verrucaria microbolum Tuck. Gen, Lich. 2: 269. 1872. 
Thallus thin, whitish to pale ash color, minutely areolate; perithecia sessile, small, 
black, depressed-globular with a minute aperture; spores colorless, broadly ellipsoid, 
4-locular, 28 » long, 16 # thick; paraphyses absent. 
On calcareous incrustations, Mill Creek Canyon, at Skinners, San Bernardino 
Mountains at 1,300 meters elevation. 
POLYBLASTIA Mass. 
Spores muriform-multilocular; otherwise as in Thelidium. 
1. Polyblastia intercedens (Nyl.) Lénnr. 
Crustaceous, light greenish gray, thin, delicately rimose; perithecia medium large, 
dull black, dimidiate; aperture depressed; paraphyses absent; spores 8, broadly 
ellipsoid, 28 to 40 » long, 16 to 18 » thick; hymenial gelatine with iodine wine red. 
Frequent in the Santa Monica Mountains on slaty schist. 
la. Polyblastia intercedens aethioboloides (Nyl.). 
Verrucaria intercedens aethioboloides Nyl. Not. Sillsk. Faun. Fl. Fenn. Forh. 5: 
276. 1861. 
Thallus sordid pale grayish brown, thin, subdeterminate; perithecia minute, dull 
black; spores ellipsoid, muriform, 18 to 20 » long, 8 to 10 » thick. 
Of the same habitat as the species but less frequent; differing from the latter in its 
smaller spores. Externally it is similar to V. aethiobola, but different in its muriform 
spores. 
THROMBIUM Wallr. 
Thallus crustaceous, uniform, scurfy-membranous, mucogelatinous when moist; 
perithecium globose, black, entire, small, immersed, only the minute black apex 
visible; paraphyses slender, persistent, without hymenial gonidia; asci clavate or 
cylindric; spores 4 to 8, colorless (with us). 
1. Thrombium epigaeum (Pers.) Schaer. 
Thallus thin, effuse, uniform, scurfy; perithecia barely visible by the punctiform 
black apex, entire; spores 8, colorless, obovate or oblong-ellipsoid, 19 to 23 m long, 
7 to 9 » thick; hymenial gelatine with iodine yellow. 
Onearth. Foothills of the Santa Monica Range near the Soldiers’ Home. Reported 
as common in North America and Europe. 
